U.S. patent number 11,166,481 [Application Number 17/081,837] was granted by the patent office on 2021-11-09 for systems and methods for reactive gas-based product treatment.
This patent grant is currently assigned to CLEAN CROP TECHNOLOGIES, INC.. The grantee listed for this patent is Clean Crop Technologies, Inc.. Invention is credited to Daniel Cavanaugh, Kevin M. Keener, Yaqoot Shaharyar, Daniel White.
United States Patent |
11,166,481 |
Keener , et al. |
November 9, 2021 |
Systems and methods for reactive gas-based product treatment
Abstract
Systems and methods disclosed herein provide an improved high
voltage plasma-based product treatment by integrating the plasma
reactor into the processing container. This unique device can
deliver a high throughput rate of raw food, without adverse effects
on quality. The system is operationally efficient, and is capable
of being scaled up or down to provide lower or higher throughput
rates, depending on the product manufacturer or processor's needs.
In particular, the system obviates the need for further
containerization or packaging of product during pasteurization
processing.
Inventors: |
Keener; Kevin M. (Ames, IA),
White; Daniel (Chesterfield, MA), Cavanaugh; Daniel
(Alexandria, VA), Shaharyar; Yaqoot (Northampton, MA) |
Applicant: |
Name |
City |
State |
Country |
Type |
Clean Crop Technologies, Inc. |
Haydenville |
MA |
US |
|
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Assignee: |
CLEAN CROP TECHNOLOGIES, INC.
(Haydenville, MA)
|
Family
ID: |
1000005920220 |
Appl.
No.: |
17/081,837 |
Filed: |
October 27, 2020 |
Prior Publication Data
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Document
Identifier |
Publication Date |
|
US 20210120848 A1 |
Apr 29, 2021 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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62926933 |
Oct 28, 2019 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61L
2/14 (20130101); A23L 3/26 (20130101); B01J
7/00 (20130101); A23B 9/06 (20130101); A23L
3/32 (20130101); A23V 2002/00 (20130101) |
Current International
Class: |
A23L
3/26 (20060101); A23B 9/06 (20060101); A23L
3/32 (20060101); A61L 2/14 (20060101); B01J
7/00 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Cleveland; Timothy C
Attorney, Agent or Firm: Cantor Colburn LLP
Parent Case Text
RELATED APPLICATIONS
The present application claims the benefit of and priority to U.S.
Provisional Patent Application No. 62/926,933, entitled "Systems
and Methods for Reactive Gas-Based Product Treatment," filed Oct.
28, 2019, the entirety of which is incorporated by reference
herein.
Claims
What is claimed:
1. A product treatment system, comprising: a container defining a
chamber and being configured to receive a feed gas and a product
within the chamber and to discharge the product from the chamber; a
cold plasma reactor disposed and configured to generate, with the
product and the feed gas within the chamber, a plasma within the
chamber, wherein: the plasma diffuses through the chamber and the
product and ionizes the feed gas to generate multiple reactive gas
species (RGS) that decontaminate the product prior to the product
being discharged from the chamber, the cold plasma reactor is
provided as first and second cold plasma reactors operably disposed
on first and second sides of the container, respectively, each of
the first and second cold plasma reactors comprises first and
second electrodes separated by an air gap, a dielectric layer
interposed between the first and second electrodes and an exterior
insulator interposed between the first and second electrodes and
the chamber, and wherein the dielectric layer and the exterior
insulator are perforated to permit gas communication between the
chamber and the air gap.
2. The product treatment system according to claim 1, wherein the
multiple RGS comprise ozone and at least one of an
oxygen-containing reactive gas species and a nitrogen-containing
reactive gas species.
3. The product treatment system according to claim 1, wherein the
multiple RGS comprise ozone and a reactive nitrogen-containing gas
species, and wherein the system is configured to provide a
concentration within the chamber of the reactive
nitrogen-containing gas species, which temporarily exceeds a
concentration of the ozone within the chamber.
4. The product treatment system according to claim 1, wherein: the
container is provided as one or more containers and the cold plasma
reactor is provided as one or more cold plasma reactors for each of
the one or more containers, and the one or more containers and the
one or more cold plasma reactors for each of the one or more
containers are operable in a continuous sequence.
5. The product treatment system according to claim 4, further
comprising at least one of: a loading bin from which each of the
one or more containers receives the product; and a bin into which
product is dischargeable from each of the one or more
containers.
6. The product treatment system according to claim 1, wherein the
container defines one or more chambers and the cold plasma reactor
is provided as one or more cold plasma reactors for each of the one
or more chambers.
7. The product treatment system according to claim 1, wherein: the
product is gravity-fed through the chamber, and the product
treatment system further comprises baffles disposed and configured
to slow the gravity-feeding of the product through the chamber.
8. The product treatment system according to claim 1, wherein: the
container defines one or more chambers and the cold plasma reactor
is provided as one or more cold plasma reactors for each of the one
or more chambers, and the product treatment system further
comprises a conveyor belt to convey the product through each of the
one or more chambers.
9. The product treatment system according to claim 1, wherein the
feed gas is at least one of received from an external supply and
generated by the cold plasma reactor.
Description
TECHNICAL FIELD
The present disclosure relates generally to systems and methods for
cold plasma-based food or biological or medical or industrial
product treatment.
BACKGROUND
Products and in particular food products such as nuts, grains,
liquids and perishable goods may be susceptible to contamination
from pathogens, microbes, viruses and various toxigenic compounds
such as mycotoxins. Treating or sterilizing these products to
enhance safety frequently involves the use of chemicals, intensive
washing, physical segregation of contaminants and various thermal
(high temperatures) treatments. that may adversely affect the
quality of the product.
BRIEF DESCRIPTION OF THE DRAWINGS
The patent or application file contains at least one drawing
executed in color. Copies of this patent or patent application
publication with color drawing(s) will be provided by the Office
upon request and payment of the necessary fee.
Various objects, aspects, features, and advantages of the
disclosure will become more apparent and better understood by
referring to the detailed description taken in conjunction with the
accompanying drawings, in which like reference characters identify
corresponding elements throughout. In the drawings, like reference
numbers generally indicate identical, functionally similar, and/or
structurally similar elements.
FIG. 1 is an illustration of a process for treating product,
according to some implementations;
FIG. 2A is an exploded view of a cold plasma reactor, according to
some implementations;
FIG. 2B is an isometric view of the cold plasma reactor of FIG. 2A,
according to some implementations;
FIG. 2C is a side view of the cold plasma reactor of FIG. 2A,
according to some implementations;
FIG. 2D is a top view of the cold plasma reactor of FIG. 2A,
according to some implementations;
FIG. 2E is a front view of the cold plasma reactor of FIG. 2A,
according to some implementations;
FIG. 2F is an exploded view of another implementation of a cold
plasma reactor;
FIG. 3 is a flow chart of an implementation of a method for
treating product;
FIG. 4 is an illustration of a system for treating product,
according to some implementations;
FIG. 5 is an illustration of another system for treating product,
according to some implementations;
FIG. 6A is an illustration of still another system for treating
product, according to some implementations;
FIG. 6B is an illustration of another implementation of the system
for treating product of FIG. 6A;
FIGS. 7A and 7B are diagrams illustrating implementations of
systems without interior reactive gas species generation and with
interior reactive gas species generation, respectively;
FIG. 8 is a diagram of an implementation of a gravity-fed system
for treating product;
FIG. 9 is a diagram of an implementation of a conveyor system for
treating product;
FIG. 10 is an illustration of volume capacity during treatment,
according to some implementations;
FIG. 11 is an illustration of a system utilizing an exterior feed
gas supply, according to some implementations;
FIG. 12A is a side view of an implementation of a cold plasma
reactor, according to some implementations;
FIG. 12B is a cross-section illustration of an implementation of a
system for treating product, according to some implementations;
FIG. 13 is an illustration of an implementation of the system of
FIG. 9 utilizing a reactive gas species dispersion fan;
FIG. 14A is a graph illustrating kinetics of gas species generated
during a 50 kilovolt (kV) treatment for 20 minutes by one
implementation of a system for treating product;
FIG. 14B is a graph illustrating kinetics of gas species generated
during a 70 kilovolt (kV) treatment for 20 minutes by one
implementation of a system for treating product;
FIG. 14C is a color photograph comparing treated product of the
implementations of FIGS. 14A and 14B with a control group,
FIG. 15A is an illustration of another system for treating product,
according to some implementations;
FIGS. 15B-15D are exploded, top, and side views of a cold plasma
reactor for use in the system of FIG. 15A, according to some
implementations;
FIG. 15E is a top view of an electrode and dielectric barrier for a
cold plasma reactor, according to some implementations;
FIG. 16A is an illustration of another system for treating product,
according to some implementations; and
FIGS. 16B-16D are exploded, top, and side views of a cold plasma
reactor for use in the system of FIG. 16A, according to some
implementations.
The details of various embodiments of the methods and systems are
set forth in the accompanying drawings and the description
below.
DETAILED DESCRIPTION
Products and in particular food products such as nuts and grains
may be susceptible to contamination from mycotoxins and microbes.
Treating or sterilizing these products to enhance safety frequently
involves the use of high temperatures that may adversely affect the
quality of the product. For example, thermal processing of a raw
food to achieve pasteurization may cook the product, altering
flavor and texture. For raw food products thermal treatments are
undesirable in many grains, seeds and nuts.
Some efforts to mitigate this undesirable effect include
pre-packaging the product, such as vacuum sealing the product in a
container (e.g. a thin plastic bag) to prevent hot steam used for
pasteurization from directly contacting the product. This still
results in heating of the product that may be undesirable, and also
adds expense to processing and limits throughput. For example, some
processing systems may individually vacuum seal an amount of nuts
as small as a kilogram or less before pasteurizing the product,
while processing shipments as large as hundreds of kilograms.
High voltage plasmas may be used for product treatment in some
implementations, allowing processing at lower temperatures,
including room temperature (e.g. approximately 20 degrees Celsius).
However, some implementations may require sealing the raw food
product within a container, which may be limited in size and
volume. Such implementations may suffer from the throughput
deficiencies noted above due to the size limitations of the
container enclosing the product and requirement to individually
package the product or small groups of product.
The systems and methods discussed herein are directed to an
improved high voltage plasma-based product treatment capable of
processing product at a high throughput rate, without changing the
visual or chemical composition of the product. The treatment does
not create any significant change in the organoleptic properties of
the product, or shorten the shelf-life such as with heating
(thermal) treatments. The system design is modular which allows for
variable throughput rates of treatment. This provides for flexible
scaling of the technology in different processing environments
which might require larger or smaller throughput (e.g. lbs/hour to
tons/hour or more). The technology may be integrated into a
containerized system where food products are introduced in a
continuous flow or stagnant (bulk) arrangement. The treatment may
also be operationally efficient, and is capable of being scaled up
or down to provide lower or higher throughput rates, depending on
the product manufacturer or processor's needs. In particular, by
integrating the plasma reactor into the processing container, the
system obviates the need for further containerization or packaging
of product during processing. The system further allows for:
Adaptability: Implementations of the reactor are widely flexible in
terms of material and geometry, and can be adapted into any
container wall or component, including rigid sidewalls for
pallet-based totes; circular or square sidewalls for grain bins;
flexible bags or conveyor belts, etc. Modularity: Because of the
wide range of materials, flexibilities, and geometries to which the
reactor can be conformed, implementations of the described system
are completely modular: adding more reactor capacity can be scaled
linearly with the treatment vessel/container size itself
Cost/material efficiency: Integrating the reactor inside the
container wall streamlines device material utilization, reducing
cost, and reducing system complexity, in many implementations.
Worker safety: By integrating the reactor into the broader system
materials, implementations of the system allow for greater distance
between workers and high voltage electric generation, improving
safety and reducing the risk of dangerous accidents. The device is
also not restricted to plasma generation within a container. The
production of reactive gas species and treatment of products may
occur in an open system or any environment which includes products
to be treated and ambient air. This is achieved through any of the
different techniques discussed herein including controlled gas
diffusion, in situ reactive gas species production within a gravity
fed system, and variable geometries of plasma generation cells.
As discussed in more detail below, in tests, implementations of the
described system reduced aflatoxin contamination in 200 grams of
peanuts from 260 parts per billion (ppb) to 105 ppb, a 60%
reduction, generating plasma at 50 kV for one hour; and to 67 ppb,
a 74% reduction, running at 70 kV for one hour.
Although discussed primarily in terms of food products, the systems
and methods discussed herein may be used for microbial or mycotoxin
mitigation of any product, including sterilization of medical
devices, food processing equipment, and industrial products without
use of antibiotic or antifungal agents that may eventually lead to
biologic immunity and reduced efficacy.
Referring first to FIG. 1, illustrated is a process 100 for
treating product, according to some implementations. A container
102 may comprise a plurality of sidewalls, a top, and a bottom,
enclosing a chamber 106. One or more of the sidewalls of the
container may comprise plasma reactors 104a, 104b (referred to
generally as plasma reactors 104 or reactors 104). A product 108
may be loaded into the container in a first step 120A. The
container may be sealed, and a high voltage plasma 110 generated by
reactors 104 at step 120B. The plasma 110 may be diffused through
the chamber 106 and product 108 at step 120B. The plasma 110 may be
generated by the reactors at voltages of 10 kV, 20 kV, 50 kV, 70
kV, 100 kV, 130 kV or any other such voltage, and may be allowed to
diffuse through the chamber for any appropriate amount of time,
such as 10 minutes, 20 minutes, 30 minutes, one hour, or any other
such period at step 120C. The plasma may be substantially at room
temperature, up to approximately 60 degrees Celsius. The plasma
ionizes a gas, such as air, generating over 75 unique reactive gas
species (RGS) if generated in ambient air, including O.sub.2,
NO.sub.2, NO.sub.3, N.sub.2O.sub.4, N.sub.2O.sub.5, H.sub.2O.sub.2,
N.sub.2O, OH or other such species, including but not limited to
formic acid, peroxide ions, dinitrogen oxide, etc. The RGS have
bactericidal, sporicidal, and fungicidal properties, and may
significantly reduce the concentrations of mycotoxins or bacteria
contaminating product 108. After being treated for the
predetermined period of time, the chamber may be emptied of product
at step 120D. The RGS products may convert back to their original
gas states (e.g. O.sub.2, N.sub.2, CO.sub.2, etc.), leaving no
chemical residues. The product may accordingly be treated without
adverse effects from heating or chemical contamination. The product
may be discharged to ground, in many implementations, and the
chamber may be evacuated of any remaining RGS (e.g. via a vacuum or
fan).
The specific composition and proportions of each RGS may be
determined by the treatment conditions and geometries of the plasma
generation device. The specific composition of RGS generated may be
changed or determined by a wide range of variables, including
voltage, temperature, humidity, air pressure, air velocity, feed
gas composition, product volume, treatment container volume, or
other such variables.
Degradation, denaturation or inactivation of different toxins,
pathogens and other food contaminants may require different
varieties and quantities of RGS. The systems and methods discussed
herein may employ treatment cycles with different rates, ranges and
parameters of each of the above variables to produce specific
`cocktails` of RGSs for each food product and contamination
issue.
In other devices which leverage the biocidal capabilities of `cold
plasma` without implementing the systems and methods discussed
herein, this distinction has not been defined or differentiated.
The generation of different gas species is critical to the
performance of the system as otherwise the contaminants will
otherwise not be removed or reduced. Accordingly, in some
implementations, the systems discussed herein may be referred to as
a multi-variable gas generation device. Depending on the type of
contaminant, the device and treatment conditions (variables) can be
adjusted to ensure the optimal amounts of RGSs are produced and
applied to each product.
The flexible generation of gases is also important to the market
value and scalability as a commercial food processing solution of
the systems and methods discussed herein. In some instances, some
RGSs may create a negative or undesirable effect on food quality.
The systems and methods discussed herein use specific geometries
and treatment parameters to ensure this does not occur.
In many implementations, ozone may be used as a feed gas in the
treatment process. In some instances, after the high voltage
current is turned off, many RGSs continue to be generated while
ozone (O.sub.3) gas rapidly declines. Accordingly, ozone may be a
catalyst for many of the other RGSs generated in the process. This
distinction is unique to implementations of the systems and methods
discussed herein, as it allows for significantly more controlled
generation of other RGSs. The integration of ozone as a feed gas
may also substantially reduce the total energy consumption to
generate a high volume of other RGSs with nitrate, nitrite, and
peroxide characteristics.
FIG. 2A is an exploded view of a cold plasma reactor 104, according
to some implementations. The reactor 104 may include a plurality of
layers 200-212, including: Exterior Insulator 200: A sufficiently
insulative non-conductive material layer, which may be at least
1/8'' or more thickness in some implementations. The insulator 200
may be of any suitable material, such as polypropylene, Teflon,
thermoplastic, or any other such non-conductive material. Electrode
202: An electrode made of a conductive or non-conductive material
capable of maintaining and distributing a high voltage electric
field in excess of 10 kV, 20 kV, 30 kV, 50 kV, 70 kV, 100 kV, 120
kV, 250 kV, or any other such value, in a controlled manner, in
various implementations. In many implementations, the electrode may
comprise a conductive material, such as aluminum or copper,
although other materials and shapes may be utilized. Dielectric
layer 204: A non-conductive material (glass, ceramic polymeric
material, mica, natural or synthetic rubbers, etc.), which may be
at least 1/16'' or greater thickness in some implementations. Frame
206a-206b (referred to generally as frame 206): A frame may support
dielectric layer 204 and a dielectric layer 208, leaving an air
gap, which may be of at least 1/4'' or greater in some
implementations. Although shown in two parts, in some
implementations, frame 206 may comprise a single piece. The frame
may be open on one or more sides as shown, and may include interior
supports in some implementations. Dielectric layer 208: A
non-conductive material (glass, ceramic, polymeric material, mica,
natural or synthetic rubbers, etc.), which may be of at least
1/16'' or greater thickness in some implementations. In many
implementations, the dielectric layer 208 may be perforated as
shown to allow air to pass between the air gap provided by frame
206 and a chamber of the container bounded by reactor 104. In many
implementations, a portion of the dielectric layer 208 may be
solid, e.g. to support an electrode 210 and associated wiring as
shown. Electrode 210: An electrode made of a conductive or
non-conductive material capable of maintaining and distributing a
high voltage electric field in excess of 10 kV, 20 kV, 30 kV, 50
kV, 70 kV, 100 kV, 130 kV, 250 kV or any other such value, in
various implementations. In many implementations, the electrode may
comprise a conductive material, such as aluminum, although other
materials and shapes may be utilized. Exterior insulator 212: A
sufficiently insulative non-conductive material layer of at least
1/8'' or more thickness. In many implementations, the exterior
insulator 212 may be perforated as shown to allow air to pass
between the air gap provided by frame 206 and a chamber of the
container bounded by reactor 104. In many implementations, a
portion of the insulator 212 may be solid, e.g. to support an
electrode 210 and associated wiring as shown.
Electrodes 202, 210 may sometimes be referred to as a high voltage
electrode and ground electrode. For example, electrode 202 may
comprise a ground electrode, and electrode 210 may comprise a high
voltage electrode. A high voltage generator (not illustrated) may
be attached to the electrodes 202, 210. The various layers of the
reactor 104 may be attached to each other via non-conductive bolts
or screws, adhesive epoxies, or other such fasteners. The edges of
the reactor may be substantially sealed, excepting open portion(s)
of frame 206, to prevent gas leakage.
FIG. 2B is an isometric view of the assembled cold plasma reactor
104 of FIG. 2A, according to some implementations. As shown, when
assembled, the layers 200-212 are substantially adjacent,
preventing gas leakage other than via the gap(s) formed by frames
206a-206b and the perforations (e.g. in layers 208, 212).
FIGS. 2C-2E are a side view, top view, and front view,
respectively, of the cold plasma reactor 104 of FIG. 2A, according
to some implementations. In the front view of FIG. 2E, locations of
frames 206a-206b are shown in dashed line, as is the location of
electrode 210. Various dimensions may be utilized for the reactor
104, allowing scaling to smaller or larger sizes depending on the
container to be used. In one such implementation, the dimensions
include:
TABLE-US-00001 Dimension Value A 16.00'' B 4.50'' C 4.50'' D 1.35''
E 1.75'' F 1.75'' G 2.00'' H 4.50'' I 20.00'' J 1.00'' K 1.00'' L
O8.00''.sub. M O0.53''.sub. N O0.25''.sub.
The dimensions may be scaled to larger or smaller values while
maintaining the same ratios, in many implementations. In other
implementations, other sizes may be used (e.g. the reactor may be
square, or have a different aspect ratio). For example, FIG. 2F is
an exploded view of another implementation of a cold plasma reactor
104'. The reactor 104' includes layers 200', 202', 204', 206',
208', 210', and 212', similar to those discussed above, but has a
square aspect ratio (e.g. 20'' by 20'', in one implementation), and
has a different configuration of perforations in layers 208', 212'
(e.g. 1'' diameter holes, in one implementation).
The plasma generation device may also be integrated into a
`reactor` or environment which is not a container. The generator
(or multiple generators) may be integrated in an open system which
is not hermetically sealed or closed, but rather controls the
specific direction of gas flow, velocity and diffusion of gas. In
effect, the generator may be integrated into any device or system
which can control the movement of gas and its contact with food
products.
FIG. 3 is a flow chart of an implementation of a method 300 for
treating product. At step 302, a product may be loaded into an
interior chamber of a container, with one or more cold plasma
reactors on or forming walls of the container. The product may be
any type of product, such as a medical implement, industrial
implement, or food product, such as nuts, grains, or other such
food products. The product need not be placed in any further
interior container (e.g. vacuum sealed pouch or other such
container) in many implementations.
At step 304, the chamber may be hermetically sealed. Sealing the
chamber may comprise closing a door, hatch, or other such opening
through which product is loaded. The chamber may include a gasket
or other feature to prevent the escape of plasma and RGS. The
chamber may contain a gas, such as atmospheric air at room
temperature. The chamber may also be open or allow for the free
flow of product using conveyors or a gravity fed system. RGSs in an
open system may be contained by air curtains, controlled diffusion
out of the system by the product under treatment or simply by
calculating the rate of diffusion of each specific gas species.
At step 306, the reactor(s) may be activated by applying a high
voltage between the electrodes. The high voltage may be generated
by an external power supply, and may be at 10 kV, 20 kV, 30 kV, 50
kV, 70 kV, 100 kV, or any other such value sufficient to generate a
plasma and RGS.
In some implementations, at step 308, a timer may be initiated and
may run for a predetermined period of time to allow the RGS
generated by the reactors to diffuse through the chamber and
product. The period of time may be predetermined based on the size
of the chamber, the RGS generation rate, the density of the
product, etc. In some implementations, the time may be 10 minutes,
20 minutes, 30 minutes, one hour, or any other such value.
In some other implementations, at step 310, a concentration of the
RGS or a particular gas (e.g. O.sub.3) within the chamber may be
measured until it has reached a concentration above a predetermined
threshold (e.g. above 7000 parts per million by volume (ppmv)).
Measuring the gas concentration may be more accurate than using
time in some implementations in which diffusion rate through the
product may be unknown or highly variable due to packing. In some
implementations, both a timer and gas concentration may be
measured.
Upon the timer expiring and/or the concentration exceeding the
threshold, at step 312, the chamber may be emptied of product. The
reactors may be deactivated, and the chamber evacuated of RGS and
plasma (e.g. via a fan or vacuum). In some implementations, a hatch
or port may be opened in the chamber to allow the product to fall
into an output bin. The hatch may be closed once the chamber is
emptied, and the process may be repeat for another batch of
product.
In another implementation, step 306 may be performed before step
302. For example, in some implementations, product may be loaded
into a first pre-treatment bin that may be hermetically sealed. The
reactors may be activated and RGS generated. The product may then
be allowed to enter the chamber with the RGS. This may speed
diffusion of the RGS throughout the product and may accelerate
treatment of the product, in some implementations.
FIG. 4 is an illustration of a system 400 for treating product,
according to some implementations. Product 108 may be loaded via a
hopper or pre-treatment bin 402 and allowed to flow onto a loading
conveyor 404. The conveyor may transport product into one or more
treatment bins 408A-408C within a hermetically sealed enclosure
406, via conveyor gates 414 corresponding to each bin. Once full
(which may be determined via a bin scale 420 integrated into each
bin 408A-408C, in some implementations), the bin may be sealed via
a bin seal 416. Each bin 408A-408C may comprise one or more
reactors 104, such as on side walls of the bin. The product may be
treated within the bin as discussed above, and once complete, may
be discharged via discharge gates 418 into an off-loading bin 410,
and thence to an output conveyor 412. By using three (or more) bins
408A-408C as shown, one bin may be undergoing treatment (e.g. at
step 422A) while a second bin is loading in preparation for
treatment (e.g. at step 422B) and a third bin is emptying after
treatment (e.g. at step 422C). This may allow for throughput of
hundreds of kilograms or several metric tons of product per hour or
more. In some implementations, RGS products generated by reactors
in one bin may be evacuated into a second bin (e.g. from a bin
finishing treatment into one loaded and ready for treatment),
accelerating the diffusion process.
FIG. 5 is an illustration of another system 500 for treating
product, according to some implementations. A loading bin 502 may
be stacked on top of a treatment bin 502 comprising one or more
reactors 104, and accessed via a seal or gate 506. At step 520A,
product 108 may be loaded into loading bin 502, and reactors 104
may be activated to generate RGS within the treatment bin 504. Once
loaded, the loading bin may be closed at step 520B. At step 520C,
the gate 506 may be opened to allow product 108 to flow into the
treatment bin 504. In some implementations, the product itself may
act as a hermetic seal during this process, preventing the RGS from
escaping into the loading bin. Once the loading bin is empty, at
step 520D, the gate 506 may be closed and the product may undergo
treatment within the treatment bin. Additional product may be
loaded into the loading bin at this time, increasing efficiency. By
activating the reactors at step 520A, this may allow the RGS to
diffuse through the empty chamber in advance, creating a more
homogenous distribution within the chamber in a shorter period of
time. This may allow for faster treatment of the product at step
520C.
FIG. 6A is an illustration of still another system 600 for treating
product, according to some implementations. Multiple sections of
the system of FIG. 5 may be joined, forming a large pre-treatment
bin 604 and large treatment bin 606. These components may be
modular, allowing for easy scalability. As discussed above, product
108 may be transported via a loading conveyor to loading hatches in
the pre-treatment bin sections. Once a predetermined amount of the
product has been loaded (e.g. as determined by a bin scale 610, in
some implementations), the product may pass through gates 608 into
treatment bins 606 with integrated reactors 104. The gates may be
closed and the product may be treated while the pre-treatment bins
are reloaded for subsequent treatment rounds. Once treatment is
complete, the treatment bins may be emptied via bin seals 612 onto
an output conveyor 614. In some implementations, the pre-treatment
and treatment bin sections may be enclosed in a hermetically sealed
chamber 616. This chamber may also include an exhaust fan, in some
implementations, for removing RGS products after treatment, and/or
for maintaining a flow of gases through the products under
treatment.
FIG. 6B is an illustration of another implementation of the system
600' for treating product of FIG. 6A, in which a single larger
pre-treatment bin 604' and treatment bin 606' are utilized rather
than modular sections. While such implementations may be less
flexible in terms of reconfiguration for scaling, they may be less
expensive to manufacture. In some implementations, additional
reactors 104 may be installed within the treatment chamber 606'
(e.g. on internal risers that do not extend fully to the top and/or
sides of the bin, allowing product to pass around or over the
reactors 104 during filling). This may allow for faster diffusion
of RGS through the product under treatment compared to only having
reactors on the sides of the bin (which may be very large, in some
implementations).
FIGS. 7A and 7B are diagrams illustrating implementations of
systems without interior reactive gas species generation and with
interior reactive gas species generation, respectively; In some
implementations, treatment systems may include multiple RGS
generation cells 104 inside of a container or throughout a
continuous flow processing point. This interior generation provides
a continuous and sustained concentration of RGSs. For example, FIG.
7A illustrates an implementation of a system 700A with a single
plasma reactor 104 on an exterior wall of a chamber for treating
product 108. The generated RGS products diffuse through the
interior of the chamber with a highest concentration 702A near the
plasma reactor 104 (e.g. 5,000 ppm); a moderate concentration 702B
farther from the plasma reactor 104 (e.g. 2,500 ppm); and a lower
concentration 702C still farther from the plasma reactor 104 (e.g.
less than 1,000 ppm). Such implementations may require longer
treatment times to ensure that the RGS products diffuse throughout
the container, or may result in a non-homogenous treatment of
product.
Conversely, FIG. 7B illustrates an implementation of a system 700B
with a plurality of plasma reactors 104 positioned within the
chamber. In many implementations, the interior plasma reactors 104
may not extend to all sides of the container, such that product 108
and RGS products may flow around, above, and/or below each reactor
104 (for example, interior reactors may be mounted on small or thin
standoffs or risers, in some implementations, with open space
below, to the side of, and above each reactor). These interior
generation points provide the unique ability to sustain RGS
concentration without requiring transporting or diffusing of gases
from one location to another (although some implementations may
further incorporate fans or other implements to diffuse the gases,
in addition to interior generation points). Such implementations
may ensure that all products treated within the system have a more
homogeneous treatment rather than the product closest to the RGS
generation points contacting larger volumes of gas or having longer
exposure periods relative to the product further from the
generation points.
In some implementations, the treatment of products using the device
may also be within an open system. This may occur using a
mechanical structure which controls the flow of product but is not
hermetically sealed or has specific control over the entry and exit
of the product. For example, FIG. 8 is a diagram of an
implementation of a gravity-fed system 800 for treating product
108. A column 802 may comprise a plurality of baffles 806 deployed
within a treatment region 804. The baffles may extend across the
treatment region 804 with openings to allow a limited amount of
product 108 to flow through to a next baffle over time. This may
stall the flow of product 108 through the system 800, resulting in
the product spending some amount of time (e.g. 10 minutes) between
each set of baffles, resulting in a total treatment time as a
multiple of the baffles (e.g. 50 minutes for 5 baffles). In some
implementations, plasma reactors may be positioned on the sides of
the chamber of the treatment region 804. In other implementations,
plasma reactors may be deployed within baffles 806. For example,
each baffle 806 may include a solid top surface to support product
above the baffle; an integrated plasma reactor; and a perforated,
slotted, or open bottom surface to allow RGS products produced by
the reactor to diffuse into the next chamber between the baffle and
a subsequent (e.g. lower) baffle 806. Advantageously, such
implementations may not require control valves or hatches at the
top and bottom of the system 800 to contain RGS products, as the
product filling openings within each baffle layer may provide a
hermetic seal as shown.
In another implementation, a conveyor may be placed within a
container which contains the gases generators using the compaction
of the product on either end of the system to provide a hermetic
seal, or an air curtain which ensures all gases treating the
products do not dissipate or move away from the product. FIG. 9 is
a diagram of such an implementation of a conveyor system 900 for
treating product. A container 902 may include a conveyor 908 for
transporting product 108 under treatment past one or more plasma
generators 104, which may be deployed on the top of the container
in some implementations, and/or on the sides of the container or
beneath the conveyor 908. In some implementations, entry hopper 904
and exit hopper 906 may limit the flow of product through the
container such that collected product 108 in each hopper 904, 906
provides a hermetic seal for RGS products within the container.
In some implementations, a particular product-to-gas ratio may need
to be maintained within treatment containers. FIG. 10 is an
illustration of volume capacity during treatment, according to some
implementations. In some implementations, the product being treated
may only occupy between approximately 5-90% of the total volume of
space within the container or treatment device, or the plasma
generators may not be able to sustain generation of the necessary
reactive gases in sufficient volumes or with sufficient diffusion
rates. For example, at left, FIG. 10 illustrates a container 1000A
having a large gas volume 1002A relative to an amount of product
108; while at right, FIG. 10 illustrates a container 1000B having a
small gas volume 1002B relative to an amount of product 108. In
some implementations, the system at right may not be able to
properly generate sufficient RGS products and treat the product.
Various methods may be used to control the amount of product under
treatment, including hatches, doors, valves, or hoppers or similar
structures having size-limited openings into the treatment
container to limit the flow of product.
In some implementations, rather than using ambient air as a
pre-reaction gas, implementations of the systems and methods
discussed herein may use ozone (O.sub.3) as a feed gas or
substitute for ambient air. In these high voltage conditions, ozone
serves as a catalyst for other reactive gas species such as
nitrates, nitrites and peroxides used for decontamination and
sterilization of food products. FIG. 11 is an illustration of a
system 1100 utilizing an exterior feed gas supply 1102, according
to some implementations. Gas supply 1102 may comprise any suitable
source of ozone, such as a pressured gas tank or an ozone
generator, and may be connected via a tube or hose to a diffuser
1104 or opening into the treatment container.
FIG. 12A is a side view of another implementation of a cold plasma
reactor 1200, according to some implementations. Similar to reactor
104, cold plasma reactor 1200 may also be used for in situ ozone
generation in the event ozone feed gas is not required or
available. A portion of reactor 1200 may include a low voltage
dielectric barrier system. For example, outer portions 1204 may
comprise a pair (or pairs) of electrodes in the upper and lower
portions of reactor 1200 to which lower voltages (e.g. 2-10 kV in
many implementations, though higher voltages may be possible in
some instances) are provided to generate ozone in regions 1206 from
oxygen in ambient air or feed oxygen or oxygen mixtures; center
portion 1202 may comprise a pair (or pairs) of electrodes in the
upper and lower portions of reactor 1200 to which higher voltages
(10-120 kV in many implementations, or higher, as discussed above)
are provided to generate RGS products 1208 from the generated
ozone. Such configurations may reduce energy consumption otherwise
required to 1.sup.st convert oxygen to ozone (the catalyst), then
subsequently generate the more stable RGSs.
In some implementations, the reactor 1200 may comprise a
multi-layered plasma generation dielectric barrier discharge (DBD)
system which uses different geometries at different intervals to
produce ozone in some areas and different RGSs in other locations.
In some such implementations, small generation points may ensure
that 100% of the treatment environment has a sustained gradient of
RGSs (homogenous treatment).
In some implementations and as discussed above, a reactor 1200, 104
may be enclosed in a barrier or baffle, or be equipped with a
shield or cover, to be deployed within a container. FIG. 12B is a
cross-section illustration of an implementation of a system 1210
for treating product, according to some implementations. A reactor
104, 1200 may be attached to or comprise a solid upper cover or top
portion 1212; and a perforated, slotted, or open bottom portion
1214 to allow RGS products to flow through. A plurality of such
shielded reactors may be deployed within a container 1216, such as
in baffles or columns extending across the container (while
allowing product to pass between neighboring reactors). Such
implementations may allow for multiple points of RGS generation
within the container 1216, speeding diffusion and treatment of
product.
Fans or blowers may also be used to diffuse RGS products through a
treatment area. FIG. 13 is an illustration of another
implementation 900' of the system of FIG. 9 utilizing an RGS
dispersion fan 1302. One or more reactors 104, 1200 may be deployed
within the container 902 (e.g. on side walls, a top surface, and/or
bottom surface). As a conveyor 908 moves product 108 through the
container 902, dispersion fan 1302 blows RGS products generated by
reactors 104, 1200 through the container, ensuring a homogenous
treatment environment.
An implementation of the systems and methods discussed herein was
tested for efficacy using whole roasted peanuts artificially
contaminated with approximately 250 ppb of aflatoxin B 1. 5 mg pure
aflatoxin was dissolved with methanol, and 1 ml of aflatoxin
solution was applied to each sample of 200 g peanuts. The samples
were placed in a hood for at least 4 hours to allow the solvent
methanol to fully evaporate.
The testing apparatus comprised a chamber with a 1/2'' electrode
gap and two 1/8'' polypropylene dielectric barriers. The electrodes
comprised 15 cm diameter spun aluminum disks, driven by an external
power supply to 50 kV and 70 kV for the tests. The chamber was 50
cm.times.38 cm.times.2.5 cm, filled with approximately 4750 ml of
room temperature air at 40% humidity. The overall dimensions of the
apparatus were 14.5 inches.times.11.4 inches.times.0.75 inches. The
test product was treated for one hour in plasma generated in room
air (at 21 degrees Celsius, and 100 kPa pressure) in an indirect
treatment at both 50 kV and 70 kV. Power consumption for the tests
were 73.3 W and 135 W, respectively. Optical absorption
spectroscopy was used to measure gas concentrations within the
chamber during activation of the reactor, and aflatoxin and
peroxide values were measured after treatment and compared to a
control sample.
FIG. 14A is a graph illustrating kinetics of gas species generated
during a 50 kV treatment for 20 minutes during the test, measured
via optical absorption spectroscopy via two fiber optic probes
within the chamber with a path length of 21 mm, at a sample rating
of 4 scans per second, averaged over one second. Similarly, FIG.
14B is a graph illustrating kinetics of gas species generated
during a 70 kV treatment for 20 minutes during the test. Running
either at 50 or 70 kV, the concentration of gas species (ozone and
nitrogen species) generated by the reactors follow a similar trend:
firstly, rapid increase with treatment time, and then gradually
decreasing after the gas species reached its peak. The decrease in
concentrations is likely caused by a slight rise in the temperature
of the gases inside the package. The maximal concentration of ozone
generated during the test at both 50 and 70 kV are approximately
the same at around 7000 ppm. Running at 70 kV, the treatment
reached the peak ozone concentration in only 9 min compared to 17
min running at 50 kV. This indicates that rate of ozone generation
at 70 kV is about two times more than at 50 kV, and also
corresponds to its approximately two times greater power
consumption. After running for 20 mins, the temperature of gas
inside the package reached 31 degrees Celsius at 70 kV, compared to
25 degrees Celsius at 50 kV.
The OAS quantitation is time dependent and provides a measure of
RGS generation. Higher NO.sub.2 and NO.sub.3 concentrations may
lead to greater detoxification. Overall, a higher RGS sum indicates
greater chemical changes in the product (e.g., detoxification).
This would be measured as the total sum area of ionization during
the plasma treatment (at the specified voltage and gap). The 70 kV
indirect treatment may provide a higher NO.sub.2 concentration
(area under the curve) than the 50 kV indirect treatment.
Post-treatment concentration measurements are time dependent due to
the formation of stable ions that cannot be quantified in the OAS.
Thus, the OAS provides a signature of the RGS created, but does not
provide a full quantitation. Specifically, N.sub.2O.sub.5 and --OH
overlap in their absorbance signature so that a reduction in ozone
concentration at longer times to form these RGS will show up as an
overall loss in the total RGS due to the difference in spectral
cross-section. Additionally, OHOON (pernitric acid) and --OOON
(pernitrous acid) may form, but it is not visible in the OAS
spectra window that is being measured.
The ROSA AFQ-FAST test (manufactured by Charm Science, Inc.) was
selected to quantitatively detect aflatoxin in the peanut samples.
Each peanut sample (200 g) was first ground using a grinder. Then
30 g sample were weighed from the ground sample and was extracted
with 150 ml of 84% Acetonitrile-16% water. The extract was
centrifuged for 10 s for clarification. The extract was then
serially diluted (1:10) with the provided AFQ dilution buffer. Then
300.mu.l diluted extract was pipetted onto the absorbent pad of the
test strips and incubated at 40 degrees Celsius for 5 minutes. The
test strips were read immediately after incubation using the
Charm-M reader. This Rapid One Step Assay is a quantitative lateral
flow test that is read in a ROSA-M Reader. The ROSA AFQ-FAST test
has been approved by USDA GIPSA (Grain Inspection, Packers and
Stockyards Administration) for corn, peanuts and 24 other
commodities. This method will only measure pure toxins and will not
quantify aflatoxin degradants.
The reduction of aflatoxin measured in the test is presented in the
table below:
TABLE-US-00002 Sample 1 Sample 2 Mean .+-. Std Reduction (ppb)
(ppb) (ppb) (%) Control 282 238 260 .+-. 31 -- 50 kV 1 h 130 80 105
.+-. 35 60% 70 kV 1 h 61 73 67 .+-. 8 74%
As shown, aflatoxin was significantly reduced by 60% at 50 kV and
74% at 70 kV through the treatment.
The treated samples were similar in appearance and quality compared
to a control group. FIG. 14C is a color photograph comparing
treated product of the implementations of FIGS. 14A and 14B with a
control group. After treatment at either 50 or 70 kV, the color of
the peanut skin appeared to be brighter, as compared to more
reddish and darker skin of the untreated peanut samples. Because of
its brighter color, the peanut kernels after treatment were more
aesthetically appealing.
To determine the effect of treatment on peanut oil, peroxide and
acid levels of each sample were measured, as shown in the table
below:
TABLE-US-00003 Sample Peroxide value (m mol/Kg) Acid value (mg
KOH/g) Control 2.86, 3.52 (3.19 .+-. 0.47) 0.54, 0.59 (0.57 .+-.
0.04) 50 KV 1 h 3.24, 4.51 (3.88 .+-. 0.90) 0.53, 0.58 (0.56 .+-.
0.04) 70 KV 1 H 3.68, 4.49 (4.09 .+-. 0.58) 0.51, 0.56 (0.54 .+-.
0.04)
The peroxide value of the peanut oil was increased slightly after
treatment, although this increase is not statistically significant.
In addition, the final peroxide value of the treated peanuts was
still below 5 mmol/kg, as commonly found in fresh oil. Acid value
of peanut oil was not affected by the treatment.
While the above example used small samples, the systems and methods
discussed herein have also been tested with larger samples, and the
results scale appropriately.
In some further implementations, cold plasma reactors may be
deployed with electrodes in close proximity to where the product
will be treated. For example, in some implementations and with some
gases, a reactor may generate short-lived RGS such as superoxides
or hydroxyl radicals that rapidly degrade (e.g. within
microseconds). Even with fan-based distribution of the generated
gasses, short-lived components may not travel more than a few
inches. These short-lived RGS may be particularly desirable for
product treatment; accordingly, in some implementations, efficacy
may be increased by having the product treatment region in close
proximity to where the plasma is generated.
FIG. 15A is an illustration of a system 1500 for treating product
with close positioning of product treatment regions, according to
some implementations. An input hopper 1502 may allow product to
drop into a treatment container (e.g. via an airlock or other gas
impermeable or semi-impermeable opening) and be carried by a
conveyor 1504 (e.g. belt, screw, etc.) past a reactor 1520 through
a region of high concentrations of generated RGS 1516, before being
deposited into an output hopper 1512 (having a similar airlock or
other gas impermeable or semi-impermeable opening). In the
implementation shown, the reactor 1520 may comprise a high voltage
single dielectric barrier discharge (SDBD) reactor (comprising a
charged electrode, dielectric barrier, and ground electrode in
close proximity) that generates plasma on or near the surfaces of
its electrodes when a voltage is applied (e.g. 10, 20, 40, 60, 80
kV or any other such value, depending on implementation). In some
implementations, RGS may be generated on both sides of the reactor
1520, and RGS from above the reactor may be recirculated to the
product treatment region 1216 (e.g. via fans and/or ducting). In
some implementations, a plurality of reactors 1520 may be placed in
line along the conveyor 1504, allowing for distributed generation
of RGS. As discussed above, this may allow for a more consistent
RGS concentration throughout the treatment process.
FIGS. 15B-15D are exploded, top, and side views of a cold plasma
reactor 1520 for use in the system of FIG. 15A, according to some
implementations. Referring first to FIG. 15B, a support or frame
1522 may comprise a plurality of compartments 1524A-1524C, referred
to generally as compartments or containers 1524. Each compartment
1524 may support a corresponding dielectric barrier 1528A-1528C,
referred to generally as a dielectric barrier 1528, which may
comprise pyrex, quartz, polyproplyene, polycarbonate, HDPE, or any
other such material capable of withstanding high voltages.
Electrodes may be attached in opposition to each other on either
side of the dielectric barrier, e.g. top electrodes 1526A-1526C
(referred to generally as a first electrode, top electrode, charged
electrode, or electrode 1526 or similar terms) and bottom
electrodes 1530A-1530C (referred to generally as a second
electrode, bottom electrode, ground electrode, or electrode 1530 or
similar terms). Although referred to here as charged and ground
electrodes 1526, 1530, in some implementations the polarities of
these electrodes may be reversed (e.g. ground electrode 1526 and
charged electrode 1530). Electrodes 1526, 1530 may be attached to
the dielectric barrier 1528 via any suitable means, such as clips,
adhesives, adhesive foil tapes, or other conductive or
non-conductive fasteners. Dielectric barrier 1528 may be solid in
some implementations, or gas permeable (e.g. perforated) in other
implementations. Electrodes 1526, 1530 may be attached via supply
leads (not illustrated) to a high voltage power supply and, during
operation, charged to a high voltage (e.g. 20, 30, 40, 60, 80 kV
RMS or any other such value) to generate plasma and RGS within a
region above and below the electrodes. In some implementations, a
conveyor belt 1532 may be positioned below the reactors to move
product through the high concentration RGS region immediately below
the reactor. In some implementations, a second reactor or set of
reactors (not illustrated) may be positioned closely below the
conveyor belt 1532, and the conveyor may be gas permeable (e.g.
mesh belts), allowing for increased RGS concentrations. As shown, a
series of reactors or sets of electrodes and dielectric barriers
may be deployed along the length of the conveyor 1532 to enable
longer duration treatments or higher throughput processing.
As shown in FIG. 15C, in some implementations, the electrodes 1526
may be centered on the dielectric barrier (and centered within a
container or compartment 1524). In other implementations, the
electrodes 1526 may be offset or non-centered.
To enable the use of higher voltages, the dielectric barrier may
need to have larger dimensions than the electrodes. For example,
FIG. 15E is a top view of an electrode 1526 and dielectric barrier
1528 for a cold plasma reactor, according to some implementations.
As shown, the electrode may be square, with length and width
dimensions n; and the dielectric barrier may be similarly square,
with length and width dimensions of at least 1.5n, and in some
implementations, at least 2n. The specific ratio of the barrier
dimensions to the electrode dimensions may be dependent on the
voltage applied between the electrodes to avoid arcing. Although
shown as square electrodes and barriers, other shapes may be used,
such as circular electrodes and barriers (e.g. with diameters n and
at least 1.5n, respectively); rectangular electrodes and barriers
as shown in FIG. 15C (e.g. with length n and width m, and with at
least length 1.5n and width 1.5m, respectively); or any other such
shapes.
While the implementations of FIGS. 15A-15D utilize a single
dielectric barrier, in other implementations, a double dielectric
barrier may be utilized with a product treatment region between the
barriers. For example, FIG. 16A is an illustration of another
system 1600 for treating product 108, according to some
implementations. As with the implementation of FIG. 15A, system
1600 may comprise an input hopper 1602, conveyor 1604, and output
hopper 1612, and product 108 may be conveyed through a product
treatment region 1616 having a high concentration of RGS. The RGS
may be generated by one or more reactors 1620 having two dielectric
barriers positioned above and below the conveyor 1604. In many such
implementations, conveyor 1604 may be gas permeable (e.g. a mesh
conveyor).
FIGS. 16B-16D are exploded, top, and side views of a cold plasma
reactor 1620 for use in the system of FIG. 16A, according to some
implementations. Similar to the reactor 1520 of FIG. 15B, reactor
1620 may comprise a frame 1622 (which may be referred to as an
upper frame or first frame, in some implementations); a compartment
or container 1624; a first electrode 1626; and a second electrode
1630. A first dielectric barrier 1628 may be attached to the upper
frame and a first electrode 1626. A second dielectric barrier 1628'
may be positioned in opposition across a product treatment region
to the first dielectric barrier 1628 (said region including a
conveyor for product, not illustrated); and may be attached to the
second electrode 1630. A lower frame 1632 may support the second
dielectric barrier 1628' and second electrode 1630. When a high
voltage is applied between first and second electrode 1626, 1630,
RGS may be generated between dielectric barriers 1628, 1628',
allowing for treatment of product within the product treatment
region. As shown in the side view of FIG. 16D, lower frame 1632 may
be positioned in close proximity and parallel to frame 1622. As
shown in FIG. 16B and as discussed above in connection with the
reactor of FIG. 15B, multiple reactors may be positioned in series,
or a reactor may comprise multiple compartments, electrodes, and
dielectric barriers positioned in series for continuous treatment
or higher throughput with consistent RGS concentrations.
As shown in the implementations of FIGS. 15A-16D, the electrodes
and dielectric barriers may comprise thin planes or planar elements
positioned parallel to each other and either adjacent or spaced
apart in the various implementations shown. Each set of electrodes
and dielectric barrier(s) may have similar shapes and dimensions
(with the barriers having larger dimensions, as discussed above in
connection with FIG. 15E, to prevent arcing), and may be centered
with one another (e.g. positioned such that the centers of each
planar element are in alignment) in some implementations, or offset
in other implementations.
Accordingly, the systems and methods discussed herein are directed
to an improved high voltage plasma-based product treatment within a
large container capable of processing product at a high throughput
rate, without adverse effects on quality from heating of the
product. The system is operationally efficient, and is capable of
being scaled up or down to provide lower or higher throughput
rates, depending on the product manufacturer or processor's needs.
In particular, by integrating the plasma reactor into the
processing container, the system obviates the need for further
containerization or packaging of product during processing.
In one aspect, the present disclosure is directed to a system for
product treatment. The system includes a cold plasma reactor,
comprising: a first electrode having a dimension n; a second
electrode, parallel to the first electrode, having a corresponding
dimension n; and a first dielectric barrier positioned between the
first electrode and the second electrode having a corresponding
dimension of at least 1.5n. The first and second electrodes are
configured to support a voltage applied between the electrodes of
at least 40 kV RMS.
In some implementations, a center of the first electrode, a center
of the second electrode, and a center of the first dielectric
barrier are aligned. In some implementations, the dimension n is
one of a length, a width, or a diameter.
In some implementations, the system includes a product application
region adjacent to the second electrode, the product application
region comprising a working gas such that when the voltage is
applied between the electrodes, one or more reactive gas species
are generated within the product application region. In a further
implementation, the second electrode comprises a first surface
adjacent to the first dielectric barrier, and an opposing second
surface adjacent to the product application region.
In some implementations, the cold plasma reactor further comprises
a second dielectric barrier positioned between the first dielectric
barrier and the second electrode, the second dielectric barrier
having a corresponding dimension of at least 1.5n. In a further
implementation, the system includes a product application region
between the first dielectric barrier and the second dielectric
barrier, the product application region comprising a working gas
such that when the voltage is applied between the electrodes, one
or more reactive gas species are generated within the product
application region.
In some implementations, the cold plasma reactor further includes:
a frame positioned between the first dielectric barrier and the
second dielectric barrier, the frame including an air gap; and a
working gas within the frame and between the first dielectric
barrier and the second dielectric barrier; and when the voltage is
applied between the electrodes, one or more reactive gas species
are generated in the working gas within the frame. In a further
implementation, the first dielectric barrier is gas permeable. In a
still further implementation, the cold plasma reactor includes a
third dielectric barrier adjacent to the first electrode and on an
opposing side of the first electrode from the first dielectric
barrier, and the third dielectric barrier is gas permeable. In
another still further implementation, the second dielectric barrier
is not gas permeable.
In some implementations, the system includes a container; and one
side of the container comprises the cold plasma reactor. In a
further implementation, at least one additional side of the
container comprises a second cold plasma reactor. In another
further implementation, the first dielectric barrier is gas
permeable; and the container comprises a product application
region, the product application region comprising a working gas
such that when the voltage is applied between the electrodes, one
or more reactive gas species are generated within the product
application region.
In some implementations, the cold plasma reactor is a first cold
plasma reactor, and the system further includes a second cold
plasma reactor adjacent to and aligned with the first cold plasma
reactor in a vertical direction; and a passage for product between
the first cold plasma reactor and the second cold plasma reactor,
the passage having an internal dimension larger than the product
and smaller than either the first cold plasma reactor or the second
cold plasma reactor.
In some implementations, the cold plasma reactor is a first cold
plasma reactor, and the system includes a second cold plasma
reactor adjacent to and aligned with the first cold plasma reactor
in a lateral direction; and a product application region extending
the length of the first and second cold plasma reactors in the
lateral direction, the product application region comprising a
working gas such that when the voltage is applied between the
electrodes, one or more reactive gas species are generated within
the product application region. In a further implementation, the
system includes a product conveyor positioned within and extending
along the product application region. In another further
implementation, the product application region is at least
partially within the first cold plasma reactor and the second cold
plasma reactor.
In some implementations, the cold plasma reactor is a first cold
plasma reactor, and the system includes one or more additional cold
plasma reactors; and a product treatment container surrounding the
first cold plasma reactor and the one or more additional cold
plasma reactors, the product treatment container comprising a
product application region subdivided into a plurality of
subregions by the first cold plasma reactor and the one or more
additional cold plasma reactors, the plurality of subregions each
comprising a working gas such that when the voltage is applied
between the electrodes of each adjacent cold plasma reactor, one or
more reactive gas species are generated within the subregion.
In another aspect, the present disclosure is directed to a method
of treating a product. The method includes providing a product in
proximity to a cold plasma reactor; and applying a voltage between
the electrodes of at least 40 kV RMS to generate reactive gas
species for treating the product.
The present disclosure has been described above with the aid of
method steps illustrating the performance of specified functions
and relationships thereof. The boundaries and sequence of these
functional building blocks and method steps have been arbitrarily
defined herein for convenience of description. Alternate boundaries
and sequences can be defined so long as the specified functions and
relationships are appropriately performed. Any such alternate
boundaries or sequences are thus within the scope and spirit of the
claimed invention. Further, the boundaries of these functional
building blocks have been arbitrarily defined for convenience of
description. Alternate boundaries could be defined as long as the
certain significant functions are appropriately performed.
Similarly, flow diagram blocks may also have been arbitrarily
defined herein to illustrate certain significant functionality. To
the extent used, the flow diagram block boundaries and sequence
could have been defined otherwise and still perform the certain
significant functionality. Such alternate definitions of both
functional building blocks and flow diagram blocks and sequences
are thus within the scope and spirit of the claimed invention. One
of average skill in the art will also recognize that the functional
building blocks, and other illustrative blocks, modules and
components herein, can be implemented as illustrated or by discrete
components, application specific integrated circuits, processors
executing appropriate software and the like or any combination
thereof.
The present disclosure may have also been described, at least in
part, in terms of one or more embodiments. An embodiment of the
present invention is used herein to illustrate the present
invention, an aspect thereof, a feature thereof, a concept thereof,
and/or an example thereof. A physical embodiment of an apparatus,
an article of manufacture, a machine, and/or a process that
embodies the present invention may include one or more of the
aspects, features, concepts, examples, etc. described with
reference to one or more of the embodiments discussed herein.
Further, from figure to figure, the embodiments may incorporate the
same or similarly named functions, steps, modules, etc. that may
use the same or different reference numbers and, as such, the
functions, steps, modules, etc. may be the same or similar
functions, steps, modules, etc. or different ones.
It should be noted that certain passages of this disclosure can
reference terms such as "first" and "second" in connection with
devices for purposes of identifying or differentiating one from
another or from others. These terms are not intended to merely
relate entities (e.g., a first coil and a second coil) temporally
or according to a sequence, although in some cases, these entities
can include such a relationship. Nor do these terms limit the
number of possible entities (e.g., coils) that can operate within a
system or environment.
It should be understood that the systems described above can
provide multiple ones of any or each of those components and these
components can be provided on either an integrated circuit or, in
some embodiments, on multiple circuits, circuit boards or discrete
components. In addition, the systems and methods described above
can be adjusted for various system parameters and design criteria,
such as number of coils, shape of coils, coil layers, etc. Although
shown in the drawings with certain components directly coupled to
each other, direct coupling is not shown in a limiting fashion and
is exemplarily shown. Alternative embodiments include circuits with
indirect coupling between the components shown.
It should be noted that although the flowcharts provided herein
show a specific order of method steps, it is understood that the
order of these steps can differ from what is depicted. Also two or
more steps can be performed concurrently or with partial
concurrence. Such variation will depend on the software and
hardware systems chosen and on designer choice. It is understood
that all such variations are within the scope of the
disclosure.
While the foregoing written description of the methods and systems
enables one of ordinary skill to make and use various embodiments
of these methods and systems, those of ordinary skill will
understand and appreciate the existence of variations,
combinations, and equivalents of the specific embodiment, method,
and examples herein. The present methods and systems should
therefore not be limited by the above described embodiments,
methods, and examples, but by all embodiments and methods within
the scope and spirit of the disclosure. It should be understood
that the application is not limited to the details or methodology
set forth in the description or illustrated in the figures. It
should also be understood that the terminology is for the purpose
of description only and should not be regarded as limiting.
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